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City begins Kimball Creek lift station retrofit; temporary bypass pumping planned
Summary
Officials reported mobilization at the Kimball Creek Lift Station retrofit, including removal of a 30-year pump, discovery of reinforced concrete that added demolition time and a planned 3-4 week full-power shutdown with diesel bypass pumping to maintain sewer service.
City staff told the Parks and Public Works Committee they have mobilized a contractor at the Kimball Creek Lift Station and will temporarily take the station offline next week while a diesel bypass system maintains sewer service during electrical replacement work.
Andrew Vining said the Kimball Creek Lift Station, the largest lift station feeding the wastewater treatment plant, is the final piece of the Wastewater Resource Facility (WRF) Phase 3 improvements. Work includes replacing electrical gear more than 25 years old and replacing pumps to better pace flow to the plant. Vining said one removed pump was about 7 feet tall and weighed approximately 6,100 pounds.
Contractors mobilized in June. Vining said demolition of the wet well uncovered reinforced concrete with rebar that staff had expected to be grout, which added a few weeks to demolition and will prompt a change order request related to unforeseen site conditions. He said the city will review the contractor’s request and the role of the project consultant in missing the detail; as-built drawings contained a general structural reference but not clear reinforcement notes.
To maintain service during the electrical work, the contractor installed a diesel bypass pumping system and a backup diesel pump. Vining said the bypass was tested and would be demonstrated for about a week prior to a full shutdown; the offline period is expected to last three to four weeks while the contractor installs a pre-inspected replacement electrical panel and completes testing.
Committee members pressed city staff about accountability for the unanticipated reinforced concrete, asking whether consultants should bear cost responsibility. Vining and other staff explained contract-document definitions and said the city will scrutinize change orders and consultant performance. Staff estimated construction completion on this lift-station work in September and said they expect to submit a change order for unforeseen conditions.
No formal vote occurred in committee. Staff said they will continue to monitor bypass testing and contractor progress and will present change orders and accountability issues in the normal contract-review process.
